Superball Flower is another powerup that you can unlock in the Story Mode. Complete the mission Spiny Shell in the main story and then Purple Toad will destroy the blocks below the floating '?' Blocks. Your job here is hit the middle '?' Block and this will unlock the Superball Flower powerup for you. Once equipped, the Superball Flower can only be used in the Super Mario Bros. Game Style. With this powerup, Mario is transformed into Superball Mario and he can shoot superballs at his enemies to kill them. However, you can only shoot one superball at one time.